Fix invalid alias name in Linq Joins (#2231)

Author: gliljas

src/NHibernate.Test/Async/Linq/ByMethod/JoinTests.cs

@@ -0,0 +1,35 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by AsyncGenerator.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+
+using System.Linq;
+using NUnit.Framework;
+using NHibernate.Linq;
+
+namespace NHibernate.Test.Linq.ByMethod
+{
+	using System.Threading.Tasks;
+	[TestFixture]
+	public class JoinTestsAsync : LinqTestCase
+	{
+		[Test]
+		public async Task MultipleLinqJoinsWithSameProjectionNamesAsync()
+		{
+			var orders = await (db.Orders
+						   .Join(db.Orders, x => x.OrderId, x => x.OrderId - 1, (order, order1) => new { order, order1 })
+						   .Select(x => new { First = x.order, Second = x.order1 })
+						   .Join(db.Orders, x => x.First.OrderId, x => x.OrderId - 2, (order, order1) => new { order, order1 })
+						   .Select(x => new { FirstId = x.order.First.OrderId, SecondId = x.order.Second.OrderId, ThirdId = x.order1.OrderId })
+						   .ToListAsync());
+
+			Assert.That(orders.Count, Is.EqualTo(828));
+			Assert.IsTrue(orders.All(x => x.FirstId == x.SecondId - 1 && x.SecondId == x.ThirdId - 1));
+		}
+	}
+}

src/NHibernate.Test/Linq/ByMethod/JoinTests.cs

@@ -0,0 +1,23 @@
+using System.Linq;
+using NUnit.Framework;
+
+namespace NHibernate.Test.Linq.ByMethod
+{
+	[TestFixture]
+	public class JoinTests : LinqTestCase
+	{
+		[Test]
+		public void MultipleLinqJoinsWithSameProjectionNames()
+		{
+			var orders = db.Orders
+						   .Join(db.Orders, x => x.OrderId, x => x.OrderId - 1, (order, order1) => new { order, order1 })
+						   .Select(x => new { First = x.order, Second = x.order1 })
+						   .Join(db.Orders, x => x.First.OrderId, x => x.OrderId - 2, (order, order1) => new { order, order1 })
+						   .Select(x => new { FirstId = x.order.First.OrderId, SecondId = x.order.Second.OrderId, ThirdId = x.order1.OrderId })
+						   .ToList();
+
+			Assert.That(orders.Count, Is.EqualTo(828));
+			Assert.IsTrue(orders.All(x => x.FirstId == x.SecondId - 1 && x.SecondId == x.ThirdId - 1));
+		}
+	}
+}

src/NHibernate/Linq/Visitors/QueryModelVisitor.cs

@@ -519,13 +519,14 @@ public override void VisitJoinClause(JoinClause joinClause, QueryModel queryMode
 		{
 			var equalityVisitor = new EqualityHqlGenerator(VisitorParameters);
 			var whereClause = equalityVisitor.Visit(joinClause.InnerKeySelector, joinClause.OuterKeySelector);
+			var querySourceName = VisitorParameters.QuerySourceNamer.GetName(joinClause);
 
 			_hqlTree.AddWhereClause(whereClause);
 
 			_hqlTree.AddFromClause(
 				_hqlTree.TreeBuilder.Range(
 					HqlGeneratorExpressionVisitor.Visit(joinClause.InnerSequence, VisitorParameters),
-					_hqlTree.TreeBuilder.Alias(joinClause.ItemName)));
+					_hqlTree.TreeBuilder.Alias(querySourceName)));
 		}
 
 		public override void VisitGroupJoinClause(GroupJoinClause groupJoinClause, QueryModel queryModel, int index)